Liquid pump, in particular for a component of a drive train of a motor vehicle

ABSTRACT

A liquid pump having an electric motor, a pump assembly, which is driven by the electric motor, and a housing wherein the electric motor and the pump assembly are arranged, wherein the housing is in the form of a one-piece, injection-moulded pot having a base and side walls, wherein the pump assembly bears against the base, and the electric motor is arranged on the open side of the housing remote from the base.

The invention relates to a liquid pump having an electric motor, a pump assembly, which is driven by the electric motor, and a housing in which the electric motor and the pump assembly are arranged.

The liquid pump is provided to be used in a drive train of a motor vehicle. For example, a stream of cooling oil can be provided by the liquid pump, with which stream of cooling oil various components in a transmission or a clutch can be cooled or also lubricated. It can also be provided that the liquid pump is used for providing a stream of hydraulic oil, which is converted in an actuator into an actuating force and an actuating stroke. For example, a clutch can be shifted with the stream of hydraulic oil provided. The pump can also be used to deliver other liquids, for example a coolant for battery cooling, transmission oil, lubricating oil, cooling oil, engine oil, transformer oil, insulating oil, etc.

Such liquid pumps are known in various forms. They can be in the form of separate units, which are then connected via lines to the component to be supplied, or they can also be mounted directly on another component, for example a transmission housing.

In a conventional construction of such a liquid pump, the housing is in multi-part form, wherein in most cases one housing part is used for the pump assembly and one housing part is used for the electric motor.

The disadvantage of the known designs is that the forces that occur during operation of the pump cannot be absorbed optimally and that there are long tolerance chains.

The object of the invention is to provide a liquid pump in which the forces that occur are absorbed optimally and which is distinguished by short tolerance chains.

In order to achieve this object, it is provided in a liquid pump of the type mentioned at the beginning that the housing is in the form of a one-piece, injection-moulded pot having a base and side walls, wherein the pump assembly bears against the base and the electric motor is arranged on the open side of the housing remote from the base. The invention is based on the fundamental idea of completely eliminating any step of mounting different housing parts on one another by using a housing that is injection moulded in one piece, which housing receives the components of the liquid pump. On the one hand, this results in very simple mounting with short tolerance chains, since all the components are mounted from one side of the housing and bear against corresponding structures of the housing. As a result, account does not have to be taken of any tolerances that can occur on mounting of different housing parts on one another. On the other hand, the forces that occur during operation of the liquid pump are absorbed and transmitted uniformly within the housing.

Preferably, an intake opening and/or a discharge opening of the liquid pump are arranged in the base of the housing. In the simplest case, the openings can be in the form of passages through the base of the housing, so that a connection to another component is obtained directly when the liquid pump is mounted with its base against the other component. Type-specific connection interfaces can be implemented with a low outlay by arranging the intake opening and the discharge opening differently in the base but otherwise producing the housing in a standardized manner.

A sealing structure, in particular a sealing groove or a cylindrical surface, is preferably associated with the opening in the base of the housing. A sealing ring can be received in the sealing groove in order to achieve axial sealing, that is to say sealing in which the contact forces that occur are applied in the axial direction. It is also possible to use a cylindrical surface into which a connecting piece of another component engages or which itself constitutes the outer surface of a connecting piece, wherein a seal bears against the cylindrical surface, in which case the sealing forces are then applied in the radial direction.

According to one embodiment of the invention, it is provided that the pump assembly has a pump housing which bears against the base. The inner surface of the base thereby serves as a reference plane on mounting of the liquid pump, and an axial play of a pump rotor within the pump housing is determined solely on the basis of the dimensions of the pump housing and of the rotor; the housing has no influence.

The pump housing is preferably centred in the housing of the liquid pump, so that no tolerance chains occur in the radial direction either.

According to one embodiment, the pump housing is fixedly connected, in particular welded or screwed, to the housing. In this manner, the axial forces that occur during operation of the liquid pump are dissipated directly into the housing.

According to a preferred embodiment of the invention there is provided a separating pot which extends between a stator and a rotor of the electric motor and separates a hydraulic side, such as hydraulic oil side of the liquid pump from a dry side, such as electronics side. The separating pot ensures that no hydraulic oil can escape from the liquid pump to the electronics side.

According to a preferred embodiment of the invention, it is provided that the separating pot has a flange which is connected to the housing. The separating pot is thus in the form of a component which is separate from the housing, so that it can be configured with a particularly small wall thickness. The separating pot can in particular be in the form of a thin-walled injection-moulded part composed of plastic.

It is particularly advantageous if the wall thickness is in the range from 0.2 to 0.4 mm, in particular in the order of 0.3 mm. This is advantageous with regard to high efficiency, since the wall thickness of the separating pot increases the air gap between the stator and the rotor. The smaller the wall thickness of the separating pot, the smaller the air gap can be.

The flange is fixedly connected, in particular welded, adhesively bonded, bolted or riveted, to the housing, so that reliable sealing is ensured. Furthermore, the forces that occur during operation are absorbed directly.

The flange thereby bears against the pump housing, so that it serves at the same time to apply the pump housing to the base.

According to an alternative form of the housing, the separating pot is formed by a pipe socket which is formed in one piece with the housing, and a separating cover which is sealingly connected to the end face of the pipe socket. This form can also be injection moulded with very high precision and a small wall thickness in the region of the pipe socket.

A printed circuit board is arranged on the open side of the housing remote from the base, which printed circuit board is encapsulated by potting compound in the housing together with the stator. The potting compound supports the separating pot from outside, so that the hydraulic forces that occur during operation can readily be absorbed. In addition, the potting compound has good heat-conducting properties, so that the thermal losses that occur are readily dissipated.

Screw openings can be integrated into the base of the housing in order to mount the liquid pump on another component and generate the contact forces that are desirable with regard to reliable sealing directly in the region of the base of the housing.

Depending on the spatial conditions in a particular case, the screw openings can also be provided at a different location in the housing, that is to say, for example, spaced apart from the base in the axial direction by half the housing or also on the open side of the housing.

The pump assembly of the liquid pump can be suitably designed in dependence on the particular requirements (in particular desired delivery pressure and desired delivery volume). For liquid pumps for actuating clutches in the drive train of motor vehicles, gear ring pumps, in particular gerotor pumps, are particularly suitable.

The pressure provided by the liquid pump can be in the order of 0.8 bar for a lubricant supply up to 45 bar for actuation of a clutch.

The invention will be described below on the basis of various embodiments, which are illustrated in the appended drawings. In these drawings:

FIG. 1 shows a plan view of a liquid pump according to a first embodiment of the invention;

FIG. 2 shows a section along the plane II-II in FIG. 1;

FIG. 3 shows the detail III in FIG. 2 on an enlarged scale;

FIG. 4 shows a perspective view from below of the liquid pump in FIG. 1;

FIG. 5 shows a view from below of the liquid pump in FIG. 1;

FIG. 6 shows a sectional view along the plane VI-VI in FIG. 5;

FIG. 7 shows the detail VII in FIG. 6 on an enlarged scale;

FIG. 8 shows a perspective plan view of the liquid pump in FIG. 1;

FIG. 9 shows a perspective view from below of a second embodiment of the invention;

FIG. 10 shows a cross section through a liquid pump according to a third embodiment;

FIG. 11 shows a cross section through a liquid pump according to a fourth embodiment;

FIG. 12 shows a cross section through a liquid pump according to a fifth embodiment;

FIG. 13 shows a cross section through a liquid pump according to a sixth embodiment;

FIG. 14 shows part of a cross section through a liquid pump according to a seventh embodiment;

FIG. 15 shows part of a cross section through a liquid pump according to an eighth embodiment;

FIG. 16 shows part of a cross section through a liquid pump according to a ninth embodiment;

FIG. 17 shows part of a cross section through a liquid pump according to a tenth embodiment.

FIGS. 1 to 8 show a first embodiment of the liquid pump. It serves to provide a stream of hydraulic oil for a drive train of a motor vehicle. This stream can be used to lubricate or to cool components of the drive train. The stream of hydraulic oil can also be provided to be converted in actuators into an actuating stroke, for example in order to shift a clutch.

The liquid pump has a housing 10 which is formed in one piece and has a pot shape, that is to say has a base 12 and side walls 14. The housing 10 is an injection-moulded part composed of plastic.

If higher strengths are required, the housing 10 can also be produced from other materials. One example is a housing composed of an aluminium alloy, which is machined at least in some portions.

Arranged in the housing 10 are a pump assembly and an electric motor.

The pump assembly has a pump housing 16 and a pump rotor 18 received therein. In the embodiment of the liquid pump shown here, there is further present an outer ring 20 which is rotatably received in the pump housing 16.

The liquid pump is here a pump of the gerotor pump type. Other types of pump are in principle also possible.

The electric motor has a rotor 22 and a stator 24. The stator 24 is stationarily arranged in the housing 10 against the side walls 14. The rotor 22 is connected in a rotationally fixed manner to a shaft 26 which is rotatably mounted in an opening of the pump housing 16. The pump rotor 18 is attached in a rotationally fixed manner to the end of the shaft 26 that is located inside the pump housing 16.

The pump housing 16 is of a size such that the pump rotor 18 can be received therein with the necessary axial play.

The pump housing 16 is centred in the interior of the housing 10 by means of radially protruding centring lugs 17 (see in particular FIG. 3), which bear against the inner wall of the housing 10. In order to avoid accumulations of material there, which can be the cause of shrinkage problems on injection moulding, the centring lugs are hollow. In this manner, a certain resilience in the radial direction is also ensured, which assists with centring.

There is provided a separating pot 28 which separates the hydraulic oil side of the pump from the electronics side. The separating pot 28 here has a flange 30, a side wall 32 of circular cylindrical cross section, and an end wall 34.

The separating pot 28 is an injection-moulded part composed of plastic, which has a wall thickness at least in the region of the side wall 32, which extends between the rotor 22 and the stator 24, in the order of 0.3 mm.

There can be used for the housing 10, the pump housing 16 and the separating pot 28 in particular thermoplastics and/or thermosetting plastics. Particularly suitable materials are PPA or PPS.

The pump assembly and the electric motor are mounted into the interior of the housing 10 from the open side thereof. The pump housing 16 thereby bears against the inner side of the base 12, and the flange 30 of the separating pot 28 presses on a circumferential contact collar 36, which is formed in one piece with the pump housing 16. The flange 30 itself is welded to the housing 10, namely to a welding collar 38 protruding in the axial direction (see in particular FIG. 3).

In order to press the pump housing 16 in the axial direction against the base 12 of the housing 10, to fix the pump housing 16 in the housing 10 and at the same time to ensure a reliable seal between the hydraulic oil side and the electronics side, the flange 30 of the separating pot 28 is welded to the welding collar 38 of the housing 10. An ultrasonic welding method, for example, can be used for this purpose.

It can be seen in FIG. 3 that the flange 30 has a groove 40 in which the welding collar 38 is positioned. The dimensions of the components relative to one another in the axial direction are such that the flange 30 presses the pump housing 16 against the base 12 of the housing 10 via the contact collar 36 and is reliably welded to the welding collar 38 before the contact collar 36 bears against the contact shoulder 42, visible in FIG. 3, of the housing 10.

On mounting of the liquid pump, the pump housing 16, on which the pump rotor 18 and the rotor 22 of the electric motor are mounted, is inserted into the interior of the housing 10. The flange 30 of the separating pot 28 is then pressed against the welding collar 38 and welded there. During this operation, the welding collar 38 is compressed in the axial direction until the pump housing 16 is pressed with its end face firmly against the base 12 of the housing 10 via the contact collar 36, which bears against the flange 30 of the separating pot 28. The weld expulsion thereby formed can be received without difficulty in the groove 40 of the flange 30.

In the welded state, the hydraulic side of the pump is reliably separated from the electronics side owing to the welded connection between the welding collar 38 and the flange 30, without the need for further seals on the housing.

On welding of the flange 30 to the welding collar 38, there can be used in principle any suitable welding method with which two weldable plastics can be connected together. Examples are a laser welding method, an ultrasonic welding method and a friction welding method.

Once the separating pot 28 has been welded to the housing 10, the stator 24 can be inserted, and there is mounted on the stator a printed circuit board 44, starting from which the coils of the stator 24 of the electric motor are electrically contacted.

In FIG. 2 there is also shown an insertion channel 46 for an electrical connector plug with which the liquid pump is electrically contacted.

After the printed circuit board has been mounted, the region of the housing in which the stator 24 and the printed circuit board 44 are arranged is filled with a potting compound. This serves on the one hand as mechanical support for the separating pot 28, and on the other hand as material for dissipating thermal losses of the stator 24.

In the base 12 of the housing 10 there are also arranged an intake opening 48 and a discharge opening 50, which open in the interior of the housing 10 in the region in which the pump unit is located. As can be seen, for example, in FIG. 6, the intake opening 48 and the discharge opening 50 extend in the axial direction through the base 12 of the housing 10.

In the embodiment of FIGS. 1 to 8, each opening has an associated sealing ring 52, which is arranged in a sealing groove 54.

For the attachment of the liquid pump, multiple screw openings 56 are integrated in one piece into the housing. In the exemplary embodiment shown, these screw openings are integrated into the base 12, so that the liquid pump can be screwed directly to a transmission housing, for example. The seals 52 thereby seal against the transmission housing in the axial direction, and the liquid pump draws from the transmission housing directly, without the need for a separate storage container and corresponding lines.

In this manner, reliable sealing and high security against the undesirable escape of hydraulic oil are ensured with a minimum number of seals, namely exactly two seals.

FIG. 9 shows a second embodiment of the invention. The same reference signs are used for the components known from the first embodiment, and, in this respect, reference is made to the explanations above.

The difference between the second and the first embodiment is that, in the second embodiment, there is used instead of two separate seals 52 a single seal 52, which has a separating web 53 which separates the intake opening 48 from the discharge opening 50.

FIG. 10 shows a third embodiment of the liquid pump. The same reference signs are used for the components known from the first two embodiments, and, in this respect, reference is made to the explanations above.

The difference between the third and the preceding embodiments is that, in the third embodiment, an axially acting seal which is arranged in a sealing groove 54 is provided for the intake opening 48, while a cylindrical sealing surface 58 is provided for the discharge opening 50, so that a radial seal is formed.

FIG. 11 shows a fourth embodiment of the liquid pump. The same reference signs are used for the components known from the preceding embodiments, and, in this respect, reference is made to the explanations above.

The difference between the fourth and the third embodiments is that, in the fourth embodiment, a radial seal is used for the intake opening 48 instead of an axial seal. For this purpose, a stepped, cylindrical outer surface 59 is formed on a connecting piece 60 which is formed in one piece with the base 12.

FIG. 12 shows a fifth embodiment of the liquid pump. The same reference signs are used for the components known from the preceding embodiments, and, in this respect, reference is made to the explanations above.

The difference between the first and the fifth embodiments is that, in the fifth embodiment, the screw openings 56 are not arranged at the level of the base 12 but are set back slightly in the axial direction towards the open side of the housing 10. In the exemplary embodiment shown, the screw openings 56 are located at approximately half the height of the housing 10.

FIG. 13 shows a sixth embodiment of the liquid pump. The same reference signs are used for the components known from the preceding embodiments, and, in this respect, reference is made to the explanations above.

The sixth embodiment differs from the fifth and the first embodiment in that the screw openings 56 are now arranged at the height of the open end of the housing 10. Sealing in the region of the intake opening 48 and the discharge opening 50 still takes place in the axial direction, in that the housing 10 is pressed in the axial direction from the plane of the screw openings 56 in the direction towards the base 12 against a counter-surface. The housing 10 can be inserted in the manner of a cartridge into, for example, a suitably configured receiving opening and can be fixedly screwed there.

FIG. 14 shows a seventh embodiment of the liquid pump. The same reference signs are used for the components known from the preceding embodiments, and, in this respect, reference is made to the explanations above.

The difference between the seventh embodiment and the preceding embodiments is that, in the seventh embodiment, the flange 30 of the separating pot 28 is adhesively bonded to the housing 10, more specifically to the contact shoulder 42. In this manner, the pump housing 16 is fixed in the housing 10 in the axial direction.

FIG. 15 shows an eighth embodiment of the liquid pump. The same reference signs are used for the components known from the preceding embodiments, and, in this respect, reference is made to the explanations above.

The difference between the eighth embodiment and the preceding embodiments is that, in the eighth embodiment, the flange 30 of the separating pot 28 is sealingly connected to the housing 10 by means of a screw connection (see screw 61). A seal can thereby be interposed in the region of contact with the contact shoulder 42.

FIG. 16 shows a ninth embodiment of the liquid pump. The same reference signs are used for the components known from the preceding embodiments, and, in this respect, reference is made to the explanations above.

The difference between the ninth embodiment and the preceding embodiments is that, in the ninth embodiment, the flange 30 of the separating pot 28 is riveted or staked to the housing 10. By way of example, a plastics rivet 62 is shown here, which rivet is deformed by heat staking such that the flange 30 of the pump housing 16 is applied to the inner side of the base 12 of the housing 10. Here too, a seal can be provided between the flange 30 and the contact shoulder 42 in order to ensure a fluid-tight connection.

FIG. 17 shows a tenth embodiment of the liquid pump. The same reference signs are used for the components known from the preceding embodiments, and, in this respect, reference is made to the explanations above.

The difference between the tenth embodiment and the preceding embodiments is that, in the tenth embodiment, the separating pot 28 is not produced completely separately from the housing 10 and then connected thereto during mounting, but the side wall 32 of the separating pot is in the form of a pipe socket which is formed in one piece with the housing 10. The base 34 of the separating pot 28 is then seated on the end face of this pipe socket, wherein the base 34 is here in the form of a separating cover. It is sealingly connected, for example welded, to the end face of the pipe socket 32.

Before the separating cover 34 is welded to the pipe socket 32, the pump housing 16 with the components 18, 20 of the pump and the rotor 22 of the electric motor is inserted into the interior of the housing 10. In order to fix these components in the axial direction, the pump housing 16 is connected to the housing 10 in the vicinity of the base 12. For this purpose, a connection 70, indicated schematically, which acts axially and/or radially, can be used. For example, the pump housing 16 can be screwed to the housing 10. It is also possible to weld the pump housing 16 inside the housing 10. 

1. A liquid pump comprising an electric motor, a pump assembly, which is driven by the electric motor, and a housing in which the electric motor and the pump assembly are arranged, wherein the housing is in the form of a one-piece, injection-moulded pot having a base and side walls, wherein the pump assembly bears against the base and the electric motor is arranged on the open side of the housing remote from the base.
 2. The liquid pump according to claim 1, wherein an intake opening and/or a discharge opening of the liquid pump is arranged in the base of the housing.
 3. The liquid pump according to claim 2, wherein a sealing structure is associated with the opening in the base of the housing.
 4. The liquid pump according to claim 1, wherein the pump assembly has a pump housing which bears against the base.
 5. The liquid pump according to claim 4, wherein the pump housing is centred in the housing.
 6. The liquid pump according to claim 4, wherein the pump housing is fixedly connected to the housing.
 7. The liquid pump according to claim 1, wherein there is provided a separating pot which extends between a stator and a rotor of the electric motor and separates a hydraulic side of the liquid pump from a dry side such as electronics side.
 8. The liquid pump according to claim 7, wherein the separating pot has a flange which is connected to the housing.
 9. The liquid pump according to claim 8, wherein the flange is fixedly connected to the housing.
 10. The liquid pump according to claim 8, wherein the flange bears against the pump housing.
 11. The liquid pump according to claim 7, wherein the separating pot is formed by a pipe socket which is formed in one piece with the housing, and a separating cover which is sealingly connected to the end face of the pipe socket.
 12. The liquid pump according to claim 1, wherein a printed circuit board is arranged on the open side of the housing remote from the base, which printed circuit board is encapsulated by potting compound in the housing together with the stator.
 13. The liquid pump according to claim 1, wherein screw openings are integrated into the base of the housing.
 14. The liquid pump according to claim 1, wherein screw openings spaced apart from the base in the axial direction are provided.
 15. The liquid pump according to claim 1, wherein the pump assembly is a gear ring pump.
 16. The liquid pump according to claim 2, wherein a sealing groove or a cylindrical surface is associated with the opening in the base of the housing.
 17. The liquid pump according to claim 4, wherein the pump housing is welded or screwed to the housing.
 18. The liquid pump according to claim 8, wherein the flange is welded, adhesively bonded, screwed or riveted to the housing.
 19. The liquid pump according to claim 8, wherein the flange bears against the pump housing and is centred in the pump housing.
 20. The liquid pump according to claim 1, wherein the pump assembly is a gerotor pump. 